Refrigeration apparatus, including defrosting means

ABSTRACT

A mechanical refrigeration system that includes improved means for defrosting the evaporator coils to remove excessive accumulations of frost and ice therefrom. Frost and ice is removed from the evaporator coils by heating means provided in the receiver with the compressed gas from the compressor being bypassed by the condenser, and the heated gas then being directed to the evaporator coils down stream from the expansion valve. During the defrosting operation, the compressor continues to operate in a normal manner, but with the gas during the defrosting operation being heated as it forms in the evaporator coils rather than being cooled as occurs when the refrigeration equipment is operated in the normal manner.

United States Patent [191 Crosby [451 Ju1y9,1974

[ REFRIGERATION APPARATUS,

INCLUDING DEFROSTING MEANS [76] Inventor:

Downey, Calif. 90241 [22] Filed: Feb. 12, 1973 [21] Appl. No.: 332,041

Related US. Application Data {62] Division of Ser. No. 138,232, April 28, 1971,

abandoned.

[52] US. Cl. 62/196, 62/278 [51] Int. Cl. F25b 41/00 [58] Field of Search 62/155, 156, 196, 197, 62/278 [56] References Cited UNITED STATES PATENTS 2,641,908 6/1953 La Porte 62/278 2,713,249 7/1955 Schordine 62/155 2,718,764 9/1955 Kramer 62/278 3,240,028 3/1966 Redfem 62/156 Redfem 62/278 Millard W. Crosby, 7050 Pellet St.,

11/1969 Kocher ..62/196 2/1971 Nussbaum.-. ..62/278 Primary Examiner-Meyer Perlin [57] ABSTRACT A mechanical refrigeration system that includes improved means for defrosting the evaporator coils to remove excessive accumulations of frost and ice therefrom. Frost and ice is removed from the evaporator coils by heating means provided in the receiver with the compressed gas from the compressor being bypassed by the condenser, and the heated gas then being directed to the evaporator coils down stream from the expansion valve. During the defrosting operation, the compressor continues to operate in 21 nor mal manner, but with the gas during the defrosting operation being heated as it forms in-the evaporator coils rather than being cooled as occurs when the re frigeration equipment is operated in the normal manner.

4 Claims, 2 Drawing Figures PATENTEBJIIL 91914 3.822562 0 E I i G I L L30 305 INVENTOR.

M/LLARD I V. CROSBY REFRIGERATION APPARATUS, INCLUDING DEFROSTING MEANS CROSS REFERENCE TO RELATED APPLICATIONS 1. Field of the Invention A refrigeration apparatus, including defrosting means.

2. Description of the Prior Art Mechanical refrigeration units have widespread use for maintaining predetermined confined spaces at desired lower temperatures to permit the storing of perishable materials. The cooling in these confined spaces is achieved by means of evaporator cooling coils through which the expanded refrigerant flows. After prolonged usage, the efficiency of the refrigeration apparatus is lowered due to the evaporator coils becoming coated with ice or frost which acts as an insulator. This accumulated frost or ice must be periodically re moved to permit the refrigeration apparatus to operate economically, and without being overloaded.

The defrosting of the evaporator coils has inthe past been a troublesome and time-consuming operation, and with the detrimental effect that the confined space in which the coils are located may heat up appreciably during the defrosting operation.

The purpose in devising the present invention is to supply improved means for defrosting evaporator coils in a relatively short time by the use of equipment that is simple and easy to use and relatively inexpensive to install as a part of the refrigeration system.

SUMMARY OF THE INVENTION In a conventional mechanical refrigeration system such as that which employs Freon or ammonia as the refrigerant, a power driven compressor is provided that has a discharge through which the gaseous refrigerant is pumped under substantial pressure to a condenser where the compressed gas is cooled. Cooling of the compressed gas in the condenser is necessary, for during the compressing of the gas it-is heated to a substantial degree-After the gas hasbeen condensed to a liquid in the condenser, it flows therefrom to a receiver tank where it accumulates as a liquid, and the liquid flowing from the receiver tank due to the pressure under which it exists therein to an expansion valve. The refrigerant in transforming from the liquid to the gaseous state must absorb heat from the coils in which it is situated, and the coils are accordingly cooled to provide the necessary refrigeration in the confined space in which they are situated. The gaseous refrigerant in the evaporator coils is continuously drawn to the suction side of a motor driven compressor where it is againcompressed and the above described cycle repeated. In a first form of the invention heat means are provided in the condenser to heat the compressed gas rather than to cool it as would nonnally occur as the gas flows through the condenser. The heated gas is then by-passed past the receiver to the evaporator coils, where the heated gas situated in the interior thereof melts the frost or ice that has formed on the exterior surfaces of the evaporator coils. During this defrosting operation, the compressor continues to operate in a normal manner, but with the condenser serving to heat the gas rather than to cool the same as normally occurs when the refrigeration equipment. is in operation.

In a second form of the invention heating means are provided in the receiver, with the compressed gas from the compressor being bypassed by the condenser, and the heated gas then being directed to the evaporator coils downstream from the expansion valve. The second form of the invention operates inthe same manner as the first form above described. In both the first and second forms of the invention, the compressor continues to operate in a normal manner.

A major object of the present invention, is to provide means for defrosting the evaporator coils in a mechanical refrigeration system, which invention is simple and easy to operate, has a simple mechanical structure, and

one that permits the defrosting of the evaporator coils of a mechanical refrigeration system in a minimum of time and with, a minimumof effort.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view of a first form of the refrigeration system; and

FIG. 2 is a diagrammatic view of a second form of the refrigeration system.

DESCRIPTION OF THE PREFERRED EMBODIMENT s I The preferred form of the invention K as shown in FIG. 2 has many of the same elements as used in the first form A of the unit, and such elements that are common to both forms are identified in FIG. 2 by the same numerals or letter previously used, but with primes being added thereto.

The conduits l2 and 18 in the second form K are connected by a bypass conduit 58 in which a normally closed solenoid operated valve60 is positioned. The heating element F is situated within the confines of the receiver D. The receiver D has a conduit 64 extending therefrom to a normally closed solenoid operated valve 66 which valve has a conduit 68 extending therefrom to a tee 30a in conduit 30'. I

A thermostatically controlled normally closed switch G is situated within the confines of the receiver D. Switch'G opens when the temperature of gas in receiver D rises above a predetermined degree. The source of power H has a conductor 70 extending therefrom to one terminal of the normally closed sole- When it is desired to defrost the coils 32 of the second form of the invention K, the switch L is closed which completes a circuit to the heating element F and concurrently opens the solenoid valves 60 and 66. The compressor B continues to operate during the defrosting operation, with hot gas being discharged therefrom ductor extending therefrom to the source of power through the conduits l2 and 58, valve 60 and conduit 18 into the receiver D, and the gas in receiver D being heated by the electrical element F. The heated gas from the receiver D flows through the conduit 64, valve 66, conduit 68, tee 30a, conduit 30, and coils 32' to heat the coils 32' to the extent that frost and ice is melted therefrom. The heated gas is returned from the coils 32' to the suction side of the compressor B through the line The heated gas from the receiver flows through the conduits 64, 68 and 30, rather than through the conduit 26, as the resistance to flow through the conduits 64, 68 and 30 is substantially less than through the conduit 26 and expansion valve 28.

After the defrosting operation is completed, the switch L is placed in the open position as shown in FIG. 2, with the valves 60 and 66 then automatically closing to permit normal operation of the refrigeration system K.

Switch 66 has conductors 54 and 56 extending therefrom to conductors 72 and 70. The same fan assembly as shown in FIG. 1 is also included as a part of the second form K of the invention.

I claim:

1. In combination with a refrigeration system of the type that alternately compresses a refrigerant gas to a liquid and expands the latter to a gas, said system including a power driven compressor, a coil type evaporator, a condenser, and an enclosed liquid receiver, with each thereof including an inlet and a discharge opening, and a first conduit connecting the discharge of said evaporator to said inlet of said compressor, a second conduit connecting said discharge of said compressor to said inlet of said condenser, a third conduit connecting said discharge of said condenser to said inlet of said receiver, and a fourth conduit connecting said discharge of said receiver to said inlet of said evaporator, with said fourth conduit having an expansion valve therein, and improvement for defrosting said evaporator, said improvement comprising:

a. electrically operated first means for heating said refrigerant liquid and gas in said receiver as said compressor continues to operate;

b. thermostatic means for preventing said refrigerant gas from being heated above a predetermined temperature in said receiver;

0. a fifth conduit extending from said receiver to said fourth conduit downstream from said expansion valve;

d. a by-pass conduit that extends between said second and third conduits; and v e. first and second valves in said by-pass conduit and fifth conduit that are closed when said system is operating to cool said coils, but said valves being opened when it is desired to defrost said evaporator coils to permit hot gas to flow from said second conduit to said third conduit and receiver and from said receiver through said fifth conduit to said evaporator coils to defrost the latter, with the resistance of flow of said gas through said by-pass conduit substantially less than that through said condenser, and the flow'of said hot, gas through said fifth conduit substantially less than through said receiver and the portion of said fourth conduit upstream from said expansion valve.

2. The combination as defined in claim 1 in which said first means includes:

f. at least one electrically operated resistance element operatively associated with said receiver to heat said gas therein when said resistance element is electrically energized; and

g. electric power conducting means for supplying electrical energy to said resistance element.

3. The combination as defined in claim 1 in which said thermostatic means is a normally closed, heat sensitive electrical switch that controls the flow of electricity from said power means to said resistance element, with said switch assuming an open position when the temperature of the refrigerant gas in said receiver rises above a predetermined maximum value.

4. The combination as defined in claim 1 in which said first and second valves are normally closed and solenoid operated, with said solenoid valves being connected to said electric power conducting means and being opened when said resistance element is electrically energized. 

1. In combination with a refrigeration system of the type that alternately compresses a refrigerant gas to a liquid and expands the latter to a gas, said system including a power driven compressor, a coil type evaporator, a condenser, and an enclosed liquid receiver, with each thereof including an inlet and a discharge opening, and a first conduit connecting the discharge of said evaporator to said inlet of said compressor, a second conduit connecting said discharge of said compressor to said inlet of said condenser, a third conduit connecting said discharge of said condenser to said inlet of said receiver, and a fourth conduit connecting said discharge of said receiver to said inlet of said evaporator, with said fourth conduit having an expansion valve therein, and improvement for defrosting said evaporator, said improvement comprising: a. electrically operated first means for heating said refrigerant liquid and gas in said receiver as said compressor continues to operate; b. thermostatic means for preventing said refrigerant gas from being heated above a predetermined temperature in said receiver; c. a fifth conduit extending from said receiver to said fourth conduit downstream from said expansion valve; d. a by-pass conduit that extends between said second and third conduits; and e. first and second valves in said by-pass conduit and fifth conduit that are closed when said system is operating to cool said coils, but said valves being opened when it is desired to defrost said evaporator coils to permit hot gas to flow from said second conduit to said third conduit and receiver and from said receiver through said fifth conduit to said evaporator coils to defrost the latter, with the resistance of flow of said gas through said by-pass conduit substantially less than that through said condenser, and the flow of said hot gas through said fifth conduit substantially less than through said receiver and the portion of said fourth conduit upstream from said expansion valve.
 2. The combination as defined in claim 1 in which said first means includes: f. at least one electrically operated resistance element operatively associated with said receiver to heat said gas therein when said resistance element is electrically energized; and g. electric power conducting means for supplying electrical energy to said resistance element.
 3. The combination as defined in claim 1 in which said thermostatic means is a normally closed, heat sensitive electrical switch that controls the flow of electricity from said power means to said resistance element, with said switch assuming an open position when the temperature of the refrigerant gas in said receiver rises above a predetermined maximum value.
 4. The combination as defined in claim 1 in which said first and second valves are normally closed and solenoid operated, with said solenoid valves being connected to said electric power conducting means and being opened when said resistance element is electrically energized. 